[Mojo Video Capture] Implement a VideoCaptureProvider that uses the video capture service

content/browser/renderer_host/media/video_capture_provider.h

Index: content/browser/renderer_host/media/video_capture_provider.h
diff --git a/content/browser/renderer_host/media/video_capture_provider.h b/content/browser/renderer_host/media/video_capture_provider.h
index fb49298f2754515305c9cc6caabf5831521223c6..f0b72bb33507b60b9a688c0ae1fdd1f3d52c0783 100644
--- a/content/browser/renderer_host/media/video_capture_provider.h
+++ b/content/browser/renderer_host/media/video_capture_provider.h
@@ -72,6 +72,8 @@ class CONTENT_EXPORT VideoCaptureProvider {
  public:
   virtual ~VideoCaptureProvider() {}
 
+  virtual void Uninitialize() = 0;
+
   // The passed-in |result_callback| must guarantee that the called
   // instance stays alive until |result_callback| is invoked.
   virtual void GetDeviceInfosAsync(